costructing a, object while pushing_back

This is a discussion on costructing a, object while pushing_back within the C++ Programming forums, part of the General Programming Boards category; hey
do I have a way to push_back a data sctructure into a vector without an outside copy? I mean: ...

Visual C++ I know supports it. Clang more then likely not does too, seeing as it is probably the compiler closes to implementing full C++11 support. It also tend to rely on the standard library shipped with GCC.
Also, push_back isn't so bad, really, since you can move the data into the vector (but emplace_back is better). Moving is usually cheap. Example:

vector<particle> Event;
Event.push_back(particle(id,pz,spin));

or

vector<particle> Event;
particle part(id,pz,spin)
Event.push_back(std::move(part));
// Don't use part after this; its state is undefined.

using C++11 isn't really an option (not that I don't have a compiler for it, its just a project requirement)

this doesn't have the need to allocate temporary memory every time its called?

Yes, it does allocate a temporary. But in C++11, you would move the temporary into the vector, thereby avoiding having to create an entire new object and copy the data over.
If you can't use C++11, then you are out of luck. Your best option would be simply to store pointers and lazily construct the objects.
If you case use TR1, you still have smart pointers at your disposal. Otherwise, there's boost.
In worst case, you can make your own to manage memory for you.